Musculocutaneous nerve
The musculocutaneous nerve is one of five major branches of the brachial plexus and supplies motor innervation to the arm and sensory innervation to the forearm.
Gross anatomy
Origin
The musculocutaneous nerve is one of two terminal branches of the lateral cord of the brachial plexus (along with the lateral root of the median nerve). It receives fibers from the C5-7 nerve roots.
Course
In the axilla, the musculocutaneous nerve courses laterally away from the axillary artery, pierces (and supplies) the coracobrachialis muscle and descends towards the elbow between biceps brachii and brachialis muscles.
In the cubital fossa, it courses lateral to the biceps tendon as the lateral cutaneous nerve of the forearm, which is simply the sensory continuation of the musculocutaneous nerve after it has distributed all its motor fibers in the anterior compartment of the arm.
Branches and supply
- muscular branches: anterior compartment of the arm (coracobrachialis, biceps brachii and brachialis muscles)
- articular branches: shoulder and elbow joints
- lateral cutaneous: lateral aspect of the forearm
Anatomical Variants
- coursing behind coracobrachialis 2
- may transmit fibers to/from median nerve 2
- supply of pronator teres 2
Related Radiopaedia articles
Anatomy: Upper limb
-
skeleton of the upper limb
- clavicle
- scapula
- humerus
- radius
- ulna
- carpal bones (mnemonic)
- metacarpals
- phalanges
- accessory ossicles of the upper limb
- accessory ossicles of the shoulder
- accessory ossicles of the elbow
-
accessory ossicles of the wrist (mnemonic)
- os centrale carpi
- os epilunate
- os styloideum
- os hamuli proprium
- lunula
- os triangulare
- trapezium secondarium
- os paratrapezium
- os radiostyloideum (persistent radial styloid)
- joints of the upper limb
-
pectoral girdle
-
shoulder joint
- articulations
- associated structures
- joint capsule
- bursae
- ligaments
-
movements
- scapulothoracic joint
- glenohumeral joint
- arm flexion
- arm extension
- arm abduction
- arm adduction
- arm internal rotation (medial rotation)
- arm external rotation (lateral rotation)
- circumduction
- blood supply - scapular anastomosis
- ossification centers
-
shoulder joint
-
elbow joint
- proximal radioulnar joint
- ligaments
- associated structures
- movements
- alignment
- blood supply - elbow anastomosis
- development
-
wrist joint
- articulations
-
ligaments
- intrinsic ligaments
- extrinsic ligaments
- radioscaphoid ligament
- dorsal intercarpal ligament
- dorsal radiotriquetral ligament
- dorsal radioulnar ligament
- volar radioulnar ligament
- radioscaphocapitate ligament
- long radiolunate ligament
- Vickers ligament
- short radiolunate ligament
- ulnolunate ligament
- ulnotriquetral ligament
- ulnocapitate ligament
- ulnar collateral ligament
- associated structures
- extensor retinaculum
- flexor retinaculum
- joint capsule
- movements
- alignment
- ossification centers
-
hand joints
- articulations
- carpometacarpal joint
-
metacarpophalangeal joints
- palmar ligament (plate)
- collateral ligament
-
interphalangeal joints
- palmar ligament (plate)
- collateral ligament
- movements
- ossification centers
- articulations
-
pectoral girdle
- spaces of the upper limb
- muscles of the upper limb
- shoulder girdle
- anterior compartment of the arm
- posterior compartment of the arm
- anterior compartment of the forearm
-
posterior compartment of the forearm (extensors)
- superficial
- deep
- hand (mnemonic)
- accessory muscles
- blood supply to the upper limb
-
arteries
- subclavian artery (mnemonic)
- axillary artery
- brachial artery (proximal portion)
- ulnar artery
- radial artery
- veins
-
arteries
- innervation of the upper limb
- intercostobrachial nerve
-
brachial plexus (mnemonic)
- branches from the roots
- branches from the trunks
- branches from the cords
- lateral cord
- posterior cord
- medial cord
- terminal branches
- lymphatic drainage of the upper limb
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